isohybrid aborts if the efi image isn't available. The 32bit ISOs don't provide
the efi.img and therefore the --uefi option for isohybrid caused to generate
non-hybrid ISOs. This issue was fixed by me in git commit
61048123d869bd74b6f05ee2995a736078716eb2 of grml-live.

The hard disk boot mode (kvm -hda $ISO or dd if=grml.iso of=/dev/sdX) doesn't
seem to work with the 32bit ISOs. Works fine with grml64 and grml96, just the
grml32 ISOs of the 2012.05 release seem to fail.